Zone control weights

ABSTRACT

A method and apparatus are provided for performing zone entity modifications to entities in a network wherein a set of generic zone entity modification commands with an estimated lower processing cost is selected for each modification. Prior zone entity modifications in the network and the associated quantity of entities and processing time associated therewith are stored in a data structure. In response to a zone entity modification request, data associated with the current request is evaluated in view of processing time for prior zone entity modifications. An estimate of processing time for the zone entity modification request is calculated for at least two sets of generic zone entity modification commands. The set of generic commands with an estimated lower processing cost is selected and applied to the current zone entity modification request.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to a network of integrated processors and storagemedia, and fabric zoning in the network. More specifically, theinvention relates to efficiently modifying one or more zone entities inthe network.

2. Description of the Prior Art

A Storage Area Network (SAN) is a network whose primary purpose is thetransfer of data between computer systems and storage elements and amongstorage elements. In one embodiment, a SAN is used for systeminterconnection in clusters. A SAN consists of a communicationinfrastructure, which provides physical connections, and a managementlayer, which organizes the connections, storage elements, and computersystems so that data transfer is secure and robust. The term SAN isusually (but not necessarily) identified with block I/O services ratherthan file access services. One or more inter-connectivity devices, suchas high speed data switches, interconnect the various data storagesystems to each other and to one or more servers that require access tothe data in the data storage systems. As servers access the data, thedata switches channel the data access requests to the appropriate datastorage systems within the storage network. Each data switch includesone or more ports dedicated to transferring data to and/or from a datastorage system or server.

A zone of resources within a storage network or another form ofdistributed computer network is an association, relation, or grouping ofresources that are arranged according to function and/or location. Zonesprovide a mechanism to increase network security and prevent data lossor corruption by controlling access between devices or user groups.Resources within the same zone can access each other, while resources indifferent zones cannot access each other. For example, in one embodimentzoning is a method of subdividing a SAN into subsets of nodes, i.e.zones, on the network where SAN nodes outside of a zone are invisible tonodes within the zone. Zones are generally used to create the following:barriers between devices that use different operating system, logicalsubsets of closed user groups, groups of devices that are separate fromdevices in the rest of a fabric, or temporary access between devices forspecific purposes. A server in the network, also known as the fabriczone server, may be used to create a zone by specifying zone members.Zero or more zones may be collected into a zoneset, and a zone may be amember of more than one zoneset. A zoneset creates a collection of zonesthat may be activated or deactivated as a single entity across allswitches in the SAN fabric. However, only one zoneset may be active fora fabric at a particular point of time. An alias is a named collectionof zone members, and the members of the alias may be part of otheraliases. The zoneset can contain zero or more zones.

With respect to zoning, the data switch is generally responsible forzone enforcement. Ports that are members of a zone can communicate witheach other but are isolated from ports in other zones. Devices, however,can belong to more than one zone. Using zoning, you can automatically ordynamically arrange connected devices into logical groups or zonesacross the physical fabric or network.

Zoning for a fabric consists of a zone definition and an activeconfiguration. Active configuration enforces the zoning in a fabric. Azone definition is a collection of zone entities that have ahierarchical relationship amongst them, with a zone entity referring toa zone set, a zone, or an alias. The zone definition can consist of zeroor more zonesets with each zoneset containing zero or more zones. Eachzone can contain zero or more zone aliases and zero or more zonemembers. A zone alias can contain zero or more zone members. An alias isa named collection of zone members. Both the zone and the zone aliascontain zero or more members, but there are difference between the zoneand zone alias. For example, an alias does not exist in the active copyof an active zone set. Its members are imploded and represented asdirect descendents of the zone containing alias. In addition, the zonedefinition can contain zero or more zones that do not belong to anyzonesets and zero or more zone aliases that do not belong to any zone.An active configuration can contain an active zoneset or no activezonesets. The active zoneset can contain zero or more zones with eachzone containing zero or more zone aliases and zero or more zone membersand with each zone alias in a zone containing zero or more zone members.In an active configuration there cannot be a zone that does not belongto a zoneset or an alias that does not belong to a zone entity sincethere is one common ancestor in an active configuration which is theactive zone set. There can be a zone set with same name in both the zonedefinition and active configuration and it can have the same ordifferent contents. Sometimes those copies are referred to as active andinactive copies of the zoneset. A zone member has to always belong toeither a zone entity or zone alias and cannot exist as a standaloneentity.

Hereinafter, the terms zone, zoneset and zone alias will be referred toas a zone entity. A zoneset in an active configuration can be created,deleted or modified. In addition a zoneset can be activated anddeactivated. Activation propagates a zoneset to the activeconfiguration. Conversely, deactivation removes the zoneset from theactive configuration.

A modification of a zone entity could mean addition to a zone entity orentities, and removal from a zone entity or entities. Removal from azone entity is different from deleting a zone entity. Removal from azone entity involves removing that entity from been part of thespecified zone entity. The zone entity can still be part of other zoneentities or not a part of any zone entity. Deletion of a zone entitymeans its removal from zone definition and/or active zone configurationand the zone entity no longer exists in zone definition and/or activezone configuration.

When making changes to zone entities in a fabric there are twoapproaches. The first approach is to delete the entire zone entity andrecreate it with the desired definition. This first approach is known inthe art as a non-incremental approach. The second approach is to modifythe zone entity by adding or removing one or more zone entities toand/or from a zone entity to reflect the new definition. This secondapproach is known in the art as an incremental approach. Depending onthe size of a zone entity and the number of changes to be made to thezone entity, one approach may be more efficient that the other approach.Selection of an approach that is not optimal, may lead to inefficientperformance.

Accordingly, there is a need for a tool that dynamically selects anoptimal modification approach, i.e. incremental or non-incremental, thatshould be used to modify each zone entity. The tool should select anoptimal approach depending on the current constitution of the zoneentity and the extent to which the zone entity needs to be modified.

SUMMARY OF THE INVENTION

This invention comprises a method and system to manage zone entitymodifications in a network, and more specifically, to determine anoptimal zone entity modification approach based upon a cost analysis.

In one aspect of the invention, a method is provided for operating anetwork. The method includes expressing one set of zone entitymodification commands of the network as a first cost, and expressing asecond set of zone entity modification commands of the network as asecond cost. The first and second sets of zone entity modificationcommands are equivalent in achieving the same result for the zone entitymodification. It is determined which of the first and second sets ofzone entity modification commands has a lower estimated cost. Based onthis determination, the set of zone entity modification commands withthe lower cost is selected. Thereafter, the zone population of thenetwork is amended with zone entity modification commands associatedwith the selected lower cost.

In another aspect of the invention, a computer system is provided with aprocessor in communication with a network of processing units andstorage media. In the network, an arrangement of grouping of resourcesis provided. A first set of zone entity modification commands to thearrangement is expressed as a first cost. Similarly, a second set ofzone entity modification commands to the arrangement is expressed as asecond cost. The first and second sets of zone entity modificationcommands are equivalent in achieving the same result for the zone entitymodification. A selection manager is provided to determine which of thesets of zone entity modification commands has a lower cost. Theselection manager selects the set of zone entity modification commandswith the lower cost, and a zone manager amends a zone entity populationin the network with the set of zone entity modification commandsassociated with the lower cost.

In yet another aspect of the invention, an article is provided with atangible computer readable carrier including computer programinstructions configured to cause a computer to detect a zonemodification request in a network, and computer program instructions tomanage a zone entity modification request. Instructions are provided toexpress a first set of zone entity modification commands of the networkas a first cost. Similarly, instructions are provided to express asecond set of zone entity modification commands of the network as asecond cost. Both the first and second sets of zone entity modificationcommands are equivalent in achieving the same result for the zone entitymodification. Instructions are also provided to determine which of thesets of commands has a lower estimated cost. In response to thedetermination, instructions are provided to select the set of zoneentity modification commands with the estimated lower cost and to amenda zone population of the network with the zone entity modificationcommands associated with the selected lower cost.

Other features and advantages of this invention will become apparentfrom the following detailed description of the presently preferredembodiment of the invention, taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a data structure.

FIGS. 2A and 2B are a flow chart illustrating a process for evaluatingcosts associated with a zone entity modification, according to thepreferred embodiment of this invention, and is suggested for printing onthe first page of the issued patent.

FIG. 3 is a block diagram of a sample table s generated and maintainedto organize the data acquired in FIGS. 2A and 2B.

FIG. 4 is a block diagram illustrating placement of one or more zonemodification managers in a computer system.

DESCRIPTION OF THE PREFERRED EMBODIMENT Overview

Create and delete sets of zone entity modification commands are similarto add and remove sets of zone entity modification commands for zoneentity configuration. Although these commands are similar and may reachthe same end result, there may be different costs associated with use ofeach set of commands. In one embodiment, costs may be interpreted asprocessing time. For example, when updating a specific zone set, thereis one cost for use of one set of commands to reach the desired result,and another cost for use of an alternative yet equivalent set ofcommands which reach the same result. Each set of commands and theirassociated costs can be expressed with an algorithm. Based on acalculated cost, an optimal set of commands may be selected for use in aparticular zone entity modification.

TECHNICAL DETAILS

In operating a network of interconnected processing units and/or astorage network with zoning of ports and logical volumes, it is known inthe art that modifications to the zone entity may be required tomaintain communication among the members of different zone entities. Azone entity is used herein to refer to a zone set, a zone, or a zonealias. Zoning entity modification takes place with one of two sets ofcommands. The first set of commands is defined as a set ofnon-incremental commands to modify a zone entity. The non-incrementalset of commands includes deleting the zone entity and recreating thezone entity with the desired definition. The second set of commands isdefined as a set of incremental commands to modify a zone entity. Theincremental set of commands includes adding or removing zone entitiesfrom the existing definition, i.e. incremental. A file is maintained totrack the historical processing time associated with individual commandsused in both zone entity modification approaches. More specifically, thefile maintains a record of the duration required for processing aspecific zone entity modification. In one embodiment, the file is in theform of a data structure to track zone usage and modification over time.

FIG. 1 is a sample data structure (100) associated with tracking costsassociated with zone entity modifications. As shown, there are twofields. Each of the fields reflects a calculated constant associatedwith processing time for the specified zone entity modification. In oneembodiment, the cost may reflect an alternate factor associated with azone entity modification and not processing time. The first field (102)identifies the specific zone entity modification, also known as theoperation. For example, as shown herein, there are four categories ofzone entity modifications—create a new zone entity (112), deleteexisting zone entity (114), add a zone entity to a zone entity (116),and remove a zone entity from a zone entity (118). Each zone entitymodification (112)-(118) has a cost associated therewith. As shownherein, the cost is shown in the second field (104) and associates acost to process each entity for each category of a zone entitymodification. In the example shown herein, the cost for creating a newzone entity is shown at (122) and is assigned the variableW_(CreateEntity), the cost for deleting existing zone entity is shown at(124) and is assigned the variable W_(DeleteEntity), the cost for addinga zone entity to a zone entity is shown at (126) and is assigned thevariable W_(AddEntityToEntity), and the cost for removing a zone entityfrom a zone entity is shown at (128) and is assigned the variableW_(RemoveEntityFromEntity). With the exception of fields (122) and(124), each of the costs are on a per zone entity member basis, meaningthat the cost is associated with each zone entity that is added orremoved from a zone entity. Fields (122) and (124) are associated withcreation and deletion of zone entity for which an optimal modificationmethod is to be determined. Accordingly, the data structure shown hereinis an example of associating a processing cost with a zone entitymodification technique.

The cost measurement associated with a zone entity modification may bemeasured based on historical data. For example, the cost measurement maybe based on historical processing time for prior zone entitymodifications. The operation time for each individual zone entitycontrol command, e.g. creating and deleting a zone entity and adding andremoving a number of entities to a zone entity, is benchmarked based onprevious operations. A variable associated with the processing time foreach command may be calculated and maintained in an associated datastructure. The cost(s) associated with the above-identified modificationselections are dynamic in that they may change over time. Accordingly,for each zone entity modification, the processing time is measured inconjunction with the number of entities in the entity or number ofentities to be added or removed from the entity subject to themodification.

FIGS. 2A and 2B are a flow chart (200) illustrating a process forevaluating costs associated with a zone entity modification. Initially,a list of zone entities that need a modification is generated (202). Thevariable N_(Total) (204) is assigned to the quantity of zone entitiesidentified at step (202), and the variable N is assigned to the integer1 (206). For zone entity_(N), the number of entities in entity_(N) isdetermined and assigned to the variable NumEntitiesInEntity_(N) (208).Similarly, the number of entities to be added to entity_(N) isdetermined and assigned to the variable NumEntitiesAdded_(N) (210), andthe number of entities to be removed from entity_(N) is determined andassigned to the variable NumEntitiesRemoved_(N) (212). Following step(212), a list of entities that need to remain in entity_(N) is generatedand assigned to the variable PreserveEntitiesList_(N) (214). Similarly,a list of entities that need to be added to entity_(N) is generated andassigned to the variable AddEntitiesToEntityList_(N) (216), and a listof entities that need to be removed from entity_(N) is generated andassigned to the variable RemoveEntitiesFromEntityList_(N) (218).Following the generation of lists at steps (214)-(218), anon-incremental zone entity modification cost is calculated and assignedto the variable NIC_(N) (220), and an incremental zone entitymodification cost is calculated and assigned to the variable IC_(N)(222). The algorithm for calculating both the incremental andnon-incremental zone entity modification is described in detail below.Following the computations at step (220) and (222), a determination isconducted as to whether the incremental zone entity modification IC_(N)has a greater cost than the non-incremental zone entity modification,NIC_(N) (224). In one embodiment, the determination at step (224) may bewhether the non-incremental zone entity modification NIC_(N) has agreater cost than the incremental zone entity modification IC_(N).Regardless of the format of the determination at step (224), the test isto determine which modification process has a greater projected cost. Ifit is determined at step (224) that the incremental zone entitymodification IC_(N) has a greater projected cost, the non-incrementalzone entity modification NIC_(N) is selected (226). Similarly, if it isdetermined at step (224) that the non-incremental zone entitymodification NIC_(N) has a greater projected cost, the incremental zoneentity modification IC_(N) is selected (228). Following steps (226) or(228) the variable N is incremented (230), followed by determination asto whether there are any more zone entities that need modification(232). In one embodiment, the variable N is compared with N_(Total), ifN_(Total) is larger than variable N, then additional zone entities needto be modified. If the variable N is larger than N_(Total), then no morezone entity needs modification. If it is determined at step (232) thatno more zone entity needs to be modified, the process is complete.However, if it is determined in step (232) that additional zone entitiesneed to be modified, the process returns to step (208) for the nextidentified zone entity that needs modification. Accordingly, each zoneentity identified for modification is evaluated to determine whichapproach is more efficient.

The flow chart illustrated above demonstrates how to select an optimalset of commands for a zone entity modification based upon costpredictions. One network may have one zone entity or a plurality of zoneentities. The calculations demonstrated above may be applied separatelyto each zone entity in the network, i.e. on a per zone entity basis.

As demonstrated in FIGS. 2A and 2B, specific data is solicited for eachzone entity subject to a modification. More specifically, for each zoneentity subject to modification the following data is assessed: thenumber of entities in the entity, the number of entities to be added tothe entity, the number of entities to be removed from the entity, thelist of entities that need to remain in the entity, the list of entitiesthat need to be added, and the list of entities that need to be removed.FIG. 3 is a block diagram (300) of a sample table (302) that isgenerated and internally maintained to organize the data acquired withprior zone entity modifications in FIGS. 2A and 2B. In one embodiment,the table (302) is stored in transient memory. As shown, the table (302)includes nine fields. The first field (304) associates an identifier forthe zone entity subject to modification. The second field (306)identifies the number of entities in the zone entity, as determined atstep (208). The third field (308) identifies the number of zone entitiesto be added to the zone entity, as determined at step (210). The fourthfield (310) identifies the number of zone entities subject to be removedfrom the subject zone entity, as determined at step (212). The fifthfield (312) identifies the list generated of the entities that need toremain in the entity in the desired definition, as determined at step(214). The sixth field (314) identifies the list generated of theentities that need to be added to the zone entity, as determined at step(216). The seventh field (316) identifies the list generated of theentities that need to be removed from the zone entity, as determined atstep (218). In addition to the fields associated with the zone entityspecificities, the table may also include the projected non-incrementalcost (318), NIC, and the projected incremental cost (320), IC.Accordingly, the data ascertained for each zone entity subject to amodification is maintained in an internal table or data structure.

Each zone modification has a processing cost associated with themodification. As shown above, the cost is calculated based upon thespecificity of the individual zone modification. A cost analysis isconducted to determine an optimal zone entity modification in view ofthe time required for the operation. The following is a mathematicalformula used to calculate the costs associated with a zone entitymodification using an incremental command modification, IC:IC=(W _(AddEntityToEntity)*NumEntitiesAdded)+(W_(RemoveEntityFromEntity)* NumEntitiesRemoved)The values for both W_(AddEntityToEntity) and W_(RemoveEntityFromEntity)are found in the data structure shown in FIG. 1, and the values forNumEntitiesAdded and NumEntitiesRemoved are determined based upon thealgorithm shown in FIGS. 2A and 2B.

Similarly, the following is a mathematical formula used to calculate thecosts associated with a zone entity modification using a non-incrementalcommand modification, NIC:NIC=W _(DeleteEntity) +W _(CreateEntity)+(W_(AddEntityToEntity)(NumEntitiesInEntity−NumEntitiesRemoved+NumEntitiesAdded))Accordingly, as demonstrated above, a set of generic commands areselected based upon a cost analysis comparison.

Based upon the data gathered for assessing projected costs for a zonemodification, a more detailed definition of a non-incremental set ofcommands and an incremental set of commands is defined. Anon-incremental set of commands to modify a zone entity may involve thefollowing sequence of commands:

-   -   1. Delete current definition of zone entity using DeleteEntity        command;    -   2. Create entity using CreateEntity command; and    -   3. For each entity that needs to remain in the entity, i.e. for        each entity in PreserveEntitiesList, and for each entity that        needs to be added to the entity, i.e. for each entity in the        AddEntitiesToList, add that entity to the entity created using        AddEntityToEntity command.        Similarly, an incremental set of commands to modify a zone        entity may involve the following sequence of commands:    -   1. For each entity in the list of entities that need to be        added, i.e. for each entity in the AddEntitiesToEntity list, add        the entity to the entity identified as subject to modification        using AddEntityToEntity command; and    -   2. For each entity in the list of entities that need to be        removed, i.e. for each entity in the RemoveEntitiesFromEntity        list, remove the entity from the entity subject to modification        using RemoveEntityFromEntity command        Accordingly, the data gathered for each entity subject to a zone        modification and stored in an internal table is utilized in        association with commands to modify the zone entity.

In one embodiment, the invention is implemented in software, whichincludes but is not limited to firmware, resident software, microcode,etc. The invention can take the form of a computer program productaccessible from a computer-useable or computer-readable medium providingprogram code for use by or in connection with a computer or anyinstruction execution system. For the purposes of this description, acomputer-usable or computer readable medium can be any apparatus thatcan contain, store, communicate, propagate, or transport the program foruse by or in connection with the instructions execution system,apparatus, or device.

FIG. 4 is a block diagram (400) illustrating placement of a selectionmanager and a zone entity manager in a computer system. The illustrationshows a server (402) with a processor (404), memory (406), and a networkadapter (408) in communication with a network (410). In one embodiment,the network is a distributed network of computer servers and clients.Similarly, in one embodiment the network is a storage area network ofshared storage media. The server (402) communicates across the network(410). Memory (406) includes a selection manager (412) and a zone entitymanager (414). As shown, the selection manager (412) is in communicationwith the zone entity manager (414). The selection manager (412) isresponsible for selection of a set of zone entity modification commands.In one embodiment, the selection is based upon the set of zone entitymodification commands with an estimated lower processing cost. The zoneentity manager (414) is responsible for amending a zone entitypopulation in the network with the set of zone entity modificationcommands determined by the selection manager (412) to have an estimatedlower cost. Both the selection manager (412) and the zone entity manager(414) are shown residing in memory (406) of the server (402). In oneembodiment, the selection manager (412) and the zone entity manager(414) may be implemented as hardware tools external to memory (406).Accordingly, the managers (412) and (414) may be implemented as asoftware tool, a hardware tool, or a combination of hardware andsoftware tools to facilitate creation and modification of a zone entityin a computer network.

Embodiments within the scope of the present invention also includearticles of manufacture comprising program storage means having encodedtherein program code. Such program storage means can be any availablemedia which can be accessed by a general purpose or special purposecomputer. By way of example, and not limitation, such program storagemeans can include RAM, ROM, EEPROM, CD-ROM, or other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium which can be used to store the desired program code meansand which can be accessed by a general purpose or special purposecomputer. Combinations of the above should also be included in the scopeof the program storage means.

The medium can be an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system (or apparatus or device) or apropagation medium. Examples of a computer-readable medium include asemiconductor or solid state memory, magnetic tape, a removable computerdiskette, random access memory (RAM), read-only memory (ROM), a rigidmagnetic disk, and an optical disk. Current examples of optical disksinclude compact disk B read only (CD-ROM), compact disk B read/write(CD-R/W) and DVD.

A data processing system suitable for storing and/or executing programcode will include at least one processor coupled directly or indirectlyto memory elements through a system bus. The memory elements can includelocal memory employed during actual execution of the program code, bulkstorage, and cache memories which provide temporary storage of at leastsome program code in order to reduce the number of times code must beretrieved from bulk storage during execution.

Input/output or I/O devices (including but not limited to keyboards,displays, pointing devices, etc.) can be coupled to the system eitherdirectly or through intervening I/O controllers. Network adapters mayalso be coupled to the system to enable the data processing system tobecome coupled to other data processing systems or remote printers orstorage devices through intervening private or public networks.

The software implementation can take the form of a computer programproduct accessible from a computer-useable or computer-readable mediumproviding program code for use by or in connection with a computer orany instruction execution system.

Advantages Over the Prior Art

A data structure is maintained in conjunction with monitoring techniquesto dynamically update processing costs associated with the genericcommands. Processing time and costs may vary over time based upon avariety of factors. For each zone entity to be modified, selection ofthe most efficient approach, i.e. incremental or non-incrementalapproach, results in an optimal zone modification. The selection of theoptimal approach depends on both current and desired definition for zoneentity and processing time of the equivalent commands needed to performthe updates. In one embodiment, the selection of the optimal approach isdone dynamically on a per entity basis. By dynamically maintaining dataassociated with processing costs, the estimate reflects real-timemodifications to entities subject to zoning in the network.

Alternative Embodiments

It will be appreciated that, although specific embodiments of theinvention have been described herein for purposes of illustration,various modifications may be made without departing from the spirit andscope of the invention. In particular, in one embodiment, dataassociated with prior zone entity modifications, including priorprocessing time and entities associated therewith, may be stored incache. This reduces latency associated with selection of a set ofcommands in that it enables the selection manage to select an optimalset of zone entity modification commands in an efficient manner.Accordingly, the scope of protection of this invention is limited onlyby the following claims and their equivalents.

1. A method for operating a network, comprising the steps of:configuring said network with a plurality of processing units andstorage media, and providing a plurality of resource zones within saidnetwork; expressing one set of zone entity modification commands of saidnetwork for a zone entity as a first cost and expressing a second set ofzone entity modification commands of said network for said zone entityas a second cost, wherein said first and second sets of zone entitymodification commands are equivalent in achieving same result for saidzone entity modification; maintaining a processing time estimate for aset of zone entity modification commands, wherein said processing timeestimate is based on historical data from at least one prior zone entitymodification in said network; determining which of said sets of zoneentity modification commands has a lower estimated cost for said zoneentity; and amending a zone entity population of said network with saidselected zone entity modification commands associated with said selectedlower cost.
 2. The method of claim 1, further comprising selecting saidzone entity modification commands with said lower cost based on saiddetermination.
 3. The method of claim 2, wherein the step of selectingsaid set of zone entity modification commands with said lower costoccurs dynamically.
 4. The method of claim 1, wherein said zone entityincludes a zone set, a zone, and a zone alias.
 5. The method of claim 1,wherein said first cost includes an incremental zone entity modificationtechnique including processing time data stored in said data structurefor adding a first zone entity to a second zone entity and for removingone of said zone entities from another of said zone entities.
 6. Themethod of claim 1, wherein said second cost is a non-incremental zoneentity modification including processing time data stored in said datastructure for deleting a zone entity, for adding a first zone entity toa second zone entity, and creating a new zone entity.
 7. A computersystem comprising: a processor in communication with a network ofprocessing units and storage media; an arrangement of a grouping ofresources in said network; a first set of modification commands to saidarrangement expressed as a first cost, and a second set of modificationcommands to said arrangement expressed as a second cost, wherein thefirst and second sets of zone entity modification commands areequivalent in achieving same result for the zone entity modification; adata structure to maintain a processing time estimate for said sets ofzone entity modification commands, wherein said estimate is based onhistorical data from at least one prior zone entity modification in saidnetwork; a selection manager to determine which of said sets of zoneentity modification commands has a lower cost; and a zone entitymanager, in communication with said selection manager, to amend a zoneentity population in said network with said set of zone entitymodification commands associated with said lower cost.
 8. The system ofclaim 7, wherein said zone entity includes a zone, a zone set, and azone alias.
 9. The system of claim 7, further comprising said selectionmanager to select said set of zone entity modification commands withsaid lower cost.
 10. The system of claim 9, wherein said selectionmanager selects one of said sets of zone entity modification commandsdynamically.
 11. The system of claim 7, wherein said second costs is anon-incremental zone entity modification that includes processing timestored in said data structure to delete a zone entity, to add a firstzone entity to a second zone entity, and to create a new zone entity.12. The system of claim 7, wherein said first cost is an incrementalzone entity modification that includes processing time data stored insaid data structure to add a first zone entity to a second zone entityand to remove one of said zone entities from another of said zoneentities.
 13. An article comprising: a computer readable data storagemedium including computer program instructions configured to cause acomputer to detect a zone entity modification request in a network andcomputer program instructions to manage said zone entity modificationrequest, comprising: instructions to express a first set of zone entitymodification commands of said network as a first cost and instructionsto express a second set of zone entity modification commands of saidnetwork as a second cost, wherein the first and second sets of zoneentity modification commands are equivalent in achieving same result forthe zone entity modification; instructions to maintain a processing timeestimate for a set of zone entity modifications commands, wherein saidestimate is based on historical data from at least one prior zone entitymodification in said network; instructions to determine which of saidsets of commands has a lower estimated cost; and instructions to amend azone entity population of said network with said zone entitymodification commands associated with said selected lower cost.
 14. Thearticle of claim 13, further comprising an instruction to select saidset of zone entity modification commands with said lower cost.
 15. Thearticle of claim 14, wherein the instruction to select said set of zoneentity modification commands with said lower costs occurs dynamically.16. The article of claim 13, wherein said first cost is an incrementalzone entity modification that includes processing time data from saiddata structure to add a first zone entity to a second zone entity and toremove one of said zone entities from another of said zone entities, andsaid second cost is a non-incremental zone entity modification thatincludes processing time from said data structure to delete a zoneentity, to add a first zone entity to a second zone entity, and tocreate a new zone entity.